Ripacord

Hello all,

I wanted to explain about my 1991 Honda Accord LX Wagon (185k on odo) not starting but turns over. The "S" sport light would flash on the dash which until recently turned solid. Have had previous problems of not starting as well. Would let it sit for a while and would then start up with "S" light flashing. Have had the alternator recently replaced and charged the battery. Thanks for any advice.

holmesnmanny

check for spark and check for fuel .. that will help narrow it down

MAD_MIKE

Passenger kick panel, look for two wire blue connector, jumper it with a wire/paperclip, turn ignition to II(ON) and record blinks(code). Report back.

proman

It's your TCU, Transmission Control Unit.

If you are handy and knows soldering, you can repair it yourself.

Take the TCU off (under passenger carpet), open it, on the PCB you should see 2 resistor burnt. It's caused by leak/dried capacitors. Replace the resistors and all capacitors will get it back to work. Youtube is your friend.

holmesnmanny

And exactly what kind of control does the tcu have over the starting of the car ?

Ripacord

I couldn't get any codes to post. Tried speaker wire & a paper clip into the OBD1 connector. However it is intermittently starting. I've noticed if keyed to on position and check engine doesn't go out it will not start. If it does go out then the car starts. From my research online it sounds like the fuel pump isn't engaging which is caused by a bad fuel "main" relay. Does anyone agree with this?

This is basically what is published in the service manual.

He's speaking about the sport light flashing. That TCU then may also be a culprit. Headaches!

MAD_MIKE

I can't say off the top of my head that that is the same wiring/terminal layout as the Accord, but I'm sure it's pretty spot on for testing.
If the ECU does not get a signal the engine will not start.(starter may engage).
But the starter will not spin if the under hood fuses are blown, ignition switch is defective, under dash fuse/relay box is not working or if (MT) the clutch switch is faulty, or the (AT) gear selector switch is faulty(P or N to allow starter).

Check all fuses, especially the 7.5A memory fuses, ECU will not retain a code if the fuse is blown.
Besides the above relays/fuses, I do not believe the ECU/TCU has any direct control over the starter operation. But if the gear selector(console) switch is not functioning the car may not start and the TCU may set a code for the console switch. And with the circuit incomplete the starter will not function.

If you place the gear selector in N does the car still not start? Have you tried jiggling the gear lever to see if the gear lights on the dash flicker?

Click on the 'techauto' link in my sig for more diagnostics.

Ripacord

You're speaking of the under-hood relay box 7.5 amp fuse number 24 which is tied to the PGM-FI ECU? The dash #2 15 amp fuse is also to the PGM-FI main relay and fuel pump.

It's starting fine now as in neutral. Dash lights do not flicker when jiggling gear lever.

There's a lot of electrical gremlins in the car! The dome and glove box lights are out as well but the hatch light functions. Forgot to mention of the faulty brake lamp indicator last month after jump starting.

Soon as I post this I go out to test once more and the check engine light stays solid and won't start in park or neutral!

Update: So today the car started again and no fuses are bad. I probably can surmise that the main relay is bad. I'm not a mechanic but work on computers so perhaps I can tackle this.

Sabrina Franks

I am having almost the exact same problem in my 1993 Honda Accord. I replaced the main relay system (which is a pain because it is under the steering wheel). The car started for 30 minutes then stalled and now I can't get it to start just turnover and to try the car needs to be jumped because the battery is dead. I am going to check the fuses but let me know if you find anything else wrong!

Ripacord

So I removed the cruise control box and the one nut to the PGM FI main relay but it won't come out. There is a black box (indicated by arrows) which I believe is the cooling fan timer in the way.

How does this come out?

Carguy86

How has progress been since your last update?

Ripacord

With help from a plumber friend of mine replaced the bad relay with a new one. He was paid in full with Guinness!

He said that he just twisted the fan timer to clear the bolts allowing the relay to be removed. I read that the flange should be bent downwards, but the timer is plastic and that would have broke the flange/tab off.

I managed to pop off the cover revealing the poor solder joints.




Starts fine every time now! Success!
Now onto the TCU!

Thanks for the advice with this dilemma.

MAD_MIKE

If the car starts fine in N but not P then it is probably the console switch that is dirty/gummed up. Take it off and clean it before blaming more costly items.

Ripacord

It now starts just fine in park as well as neutral. The problem now is that it is in "limp mode" with the solid sport light on the dash. The gears need to be manually shifted, otherwise the A/T is sluggish from a standing start. I suppose though that will cause wear on the transmission linkage.

I'm just pleased that the car is running for now.